EP0431426B1 - Verfahren und Vorrichtung zum Betrieb einer Filterzentrifuge - Google Patents

Verfahren und Vorrichtung zum Betrieb einer Filterzentrifuge Download PDF

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Publication number
EP0431426B1
EP0431426B1 EP90122453A EP90122453A EP0431426B1 EP 0431426 B1 EP0431426 B1 EP 0431426B1 EP 90122453 A EP90122453 A EP 90122453A EP 90122453 A EP90122453 A EP 90122453A EP 0431426 B1 EP0431426 B1 EP 0431426B1
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EP
European Patent Office
Prior art keywords
hydroextraction
time
filter cake
determined
filter
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
EP90122453A
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German (de)
English (en)
French (fr)
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EP0431426A1 (de
Inventor
Reinhold Dr. Dipl.-Ing. Schilp
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Mannesmann Demag Krauss Maffei GmbH
Original Assignee
Krauss Maffei AG
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B04—CENTRIFUGAL APPARATUS OR MACHINES FOR CARRYING-OUT PHYSICAL OR CHEMICAL PROCESSES
    • B04B—CENTRIFUGES
    • B04B11/00—Feeding, charging, or discharging bowls
    • B04B11/04—Periodical feeding or discharging; Control arrangements therefor
    • B04B11/043—Load indication with or without control arrangements

Definitions

  • the invention relates to a method for operating a filter centrifuge according to the preamble of patent claim 1.
  • the level in the rotating drum decreases more or less quickly depending on the filtration properties. So that a certain height of the filter cake in the drum can be reached, one or more times suspension in the drum is refilled up to the maximum filling level, the level being monitored by means of a level controller.
  • a sensor can be used which can detect a change in the surface condition of the filter material in the drum, so that the time of immersion of the liquid surface in the filter cake can be determined. Such a sensor is disclosed for example in DE-OS 37 26 227.
  • a method for separating sugar from a sugar suspension in which a washing process is controlled depending on the surface density of the filter cake.
  • the areal density is determined, for example, by the absorption of gamma radiation.
  • Another method for monitoring sugar centrifuges is known from DE-A-32 15 915.
  • the surface of the filter cake of a centrifuge is monitored using a reflection method and the time of immersion of the liquid surface is determined.
  • a method according to the preamble of claim 1 is known from DE-C-36 15 013.
  • the flow rate of the outflowing liquid is monitored during the dry spin process and the dry spin process is controlled as a function of the flow rate. It is therefore necessary to monitor the dry spin cycle yourself and to take additional measures to determine the liquid speed.
  • the object of the invention is to minimize the individual cycle times despite fluctuations in the filtration conditions and to significantly increase the throughput of the filter centrifuge with a constant degree of washout and constant low final residual moisture.
  • the level in the rotating centrifuge drum is measured continuously or at time intervals with a measuring device and the time course of the level is registered.
  • the immersion points of the mother liquor or the washing liquid in the filter cake are determined. H. the times at which the liquid is filtered off to such an extent that it begins to disappear in the filter cake. From the temporal change in the filling level and the immersion times, the optimal number of filling cycles, the optimal start of the washing cycle and the required spin drying time are concluded, so that a desired final residual moisture of the filter cake is achieved with a minimal total cycle time.
  • the filling, dehumidifying and washing processes in the filter centrifuge are controlled independently of fluctuations in the task in such a way that the throughput is maximized with a constant degree of washing out and constant final residual moisture.
  • the invention is based on the finding that all the fluctuations and imponderables that affect the filtration, washing and drying spin times are expressed in the rate at which the liquids decrease in height. These can be due to the suspension properties such as grain shape, average grain size (d-p50), shape and slope of the total curve of the grain size analysis, fine particles, feed concentration, liquid temperature, viscosity, interfacial tension etc. or they can also be due to the operating properties of the filter media or the filter centrifuge.
  • suspension properties such as grain shape, average grain size (d-p50), shape and slope of the total curve of the grain size analysis, fine particles, feed concentration, liquid temperature, viscosity, interfacial tension etc.
  • Fluctuations from batch to batch can be compensated for by changing cycle times and incorrect batches whose solids discharge is too moist are avoided.
  • Required regeneration steps such as backing up the base layer, clearing out the base layer or regenerating filter medium are displayed and triggered automatically. In spite of a discontinuous driving style, a uniform product quality is achieved and downstream devices such as dryers etc. can be driven to their performance limits.
  • FIG. 1 The work processes taking place successively in a discontinuous filter centrifuge are shown in FIG. 1. After several filter processes in which a filter cake with the desired thickness has been formed, the filter cake is washed with a washing liquid which is introduced into the drum and passes through the filter cake.
  • the filter cake is then dried in a dry spin cycle without adding any additional liquid.
  • This dry spin process can optionally be followed by a further drying process in which the filter cake z. B. can be removed by supplying hot air or the like. Liquid.
  • the dried filter cake is then removed from the centrifuge drum, for example by means of a peeling knife arranged in the centrifuge drum.
  • the centrifuge drum can then either be refilled or a regeneration process follows. In this regeneration process, the solid fraction remaining in the drum during peeling, the so-called base layer, is removed, for example by backwashing, and filters are replaced if necessary.
  • FIG. 2 shows the course over time of the fill level and the filter cake thickness in the above-described operations of the filter centrifuge for one work cycle.
  • the washing process is started, in which a washing liquid is fed to the drum and filtered through the filter cake by centrifugation. As soon as the washing liquid has completely penetrated the surface of the filter cake, that is the immersion point ET, the filtering process is continued with the dry spin process without adding any additional liquid. The drum is then cleared and, if necessary, regenerated.
  • the total cycle time t is relatively long in the case of products that are difficult to filter, the time fraction required for the dry centrifugation being particularly decisive.
  • the height of the filter cake decreases only slightly during the spin drying process.
  • Figure 3 shows schematically the decrease in height of the washing liquid applied before the spin-drying phase.
  • the decreasing layer height h is measured and stored at regular intervals and the differential quotient dh / dt is continuously formed in a process computer from the decrease in height of the washing liquid layer above the filter cake.
  • the total layer height decreases until the filter cake thickness h ET is reached, at which the liquid on the cake surface disappears and is immersed in the filter cake.
  • the to this immersion point belonging time t ET is registered.
  • the spin time t S starts to spin dry the solid cake.
  • This essential time t S for the cycle duration can be determined from the values h ET and dh / dt measured for each batch and a constant K which is dependent on the machine data (size) and the drum speed.
  • the fluctuating filtration properties depend on the fluctuating suspension properties such as grain shape, average grain size (d-p50), shape and slope of the total curve of the grain size analysis, fines, feed concentration, liquid temperature, viscosity, interfacial tension, etc. These product properties are determined by the parameters h ET and dh / dt recorded with sufficient accuracy.
  • the dry spin time t S required for the respective batch to achieve the desired residual moisture is calculated from: t S ⁇ K a ⁇ H ET /H ETo ⁇ b t So ⁇ (ie / dt) O / (ie / dt) ⁇ c
  • the ratio of the filter cake heights when immersing the washing liquid (h ET ) and when immersing the mother liquor (h ETo ) is formed; the removal speeds when immersing the mother liquor (dh / dt) o and when immersing the washing liquid (dh / dt) are calculated and also related.
  • the values determined in this way are exponentiated by the exponents b or c and multiplied by the value K a , which depends on the machine data. Finally, the value thus obtained is multiplied by a time value t So for a normal dry spin cycle.
  • the quantity t So can be calculated, formed from an empirical value or measured in a previous spinning process.
  • the constant exponents a, b and c can be calculated or be determined by experiments; they do not change for the individual batches.
  • FIG. 4 shows the filling level curve over time for two differently filtering products due to the influence of the batch-dependent suspension feed.
  • the solid line shows the normal batch process with the operations: Filling, filtering, adding washing liquid, spinning to the immersion point ET0, dry spinning, clearing out
  • the dashed line shows the batch process for grain enlargement and increasing the feed concentration.
  • the rate of rise is somewhat slower when filling because the product filters better.
  • the filling valve is closed and the liquid level drops more steeply.
  • the washing liquid can be added immediately; the water level drops faster.
  • the immersion point ET1 the dry spin phase begins, which 1 can be much shorter than in the normal case because of the steep drop (ie / dt). If the desired residual moisture has been reached, clearing can already start at R1. The cycle can then be repeated.
  • Figure 5 shows a schematic representation of the process control.
  • the quantities h and h ET to be measured on the centrifuge as a function of time are entered into the computer. From the differential quotient dh / dt during the filtering off of the mother liquor at point W and the differential quotient dh / dt during the washing liquid outflow at point ET, the batch-dependent change in the drying time required to reach a certain residual moisture at point R is calculated in a process computer and specified as the cycle time.
  • the mean value from the linearized course of the decrease in height over time or the difference quotient ⁇ h / ⁇ t of the quantities can be determined.
  • An analog computer or a digital computer can be used as the process computer.

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  • Centrifugal Separators (AREA)
EP90122453A 1989-12-04 1990-11-26 Verfahren und Vorrichtung zum Betrieb einer Filterzentrifuge Expired - Lifetime EP0431426B1 (de)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE3940057A DE3940057A1 (de) 1989-12-04 1989-12-04 Verfahren und vorrichtung zum betrieb einer filterzentrifuge
DE3940057 1989-12-04

Publications (2)

Publication Number Publication Date
EP0431426A1 EP0431426A1 (de) 1991-06-12
EP0431426B1 true EP0431426B1 (de) 1994-01-26

Family

ID=6394776

Family Applications (1)

Application Number Title Priority Date Filing Date
EP90122453A Expired - Lifetime EP0431426B1 (de) 1989-12-04 1990-11-26 Verfahren und Vorrichtung zum Betrieb einer Filterzentrifuge

Country Status (5)

Country Link
US (1) US5093010A (ja)
EP (1) EP0431426B1 (ja)
JP (1) JPH03270750A (ja)
DE (2) DE3940057A1 (ja)
ES (1) ES2048391T3 (ja)

Families Citing this family (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE4204805A1 (de) * 1992-02-18 1993-08-19 Henkel Kgaa Verfahren zum kontinuierlichen betreiben eines separators und zusatzeinrichtung fuer diesen separator
US5897786A (en) * 1997-03-24 1999-04-27 The Western States Machine Company Method and apparatus for determining thickness of a charge wall being formed in a centrifugal machine
US6296774B1 (en) 1999-01-29 2001-10-02 The Western States Machine Company Centrifuge load control for automatic infeed gate adjustment
DE102013111576A1 (de) 2013-10-21 2015-04-23 Gea Mechanical Equipment Gmbh Verfahren zur Klärung eines fließfähigen Produktes mit einer Zentrifuge, insbesondere einem Separator

Family Cites Families (16)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
BE516155A (ja) * 1951-12-12
US3117233A (en) * 1961-06-21 1964-01-07 American Plant Equipment Compa Filter cake thickness detector for filtering apparatus
US3204766A (en) * 1961-07-17 1965-09-07 Industrial Filter Pump Mfg Co Filter cake thickness detector
US3141846A (en) * 1962-04-05 1964-07-21 Western States Machine Co Load control unit for cyclical centrifugal installation
DE1186411B (de) * 1963-10-03 1965-01-28 Krauss Maffei Ag Schaelzentrifuge, insbesondere fuer langsam filtrierende Suspensionen
DE2441849A1 (de) * 1974-08-31 1976-03-18 Titus Hans Joachim Vollautomatische fuellsteuerung fuer zentrifugen
US4014498A (en) * 1975-01-15 1977-03-29 Alfa-Laval Ab Method and apparatus for centrifuging sludge-containing liquids
DE2525232A1 (de) * 1975-06-06 1976-12-16 Riedel De Haen Ag Vorrichtung zur messung der fuellschichthoehe einer siebschleuder
CH604907A5 (ja) * 1975-11-14 1978-09-15 Sandoz Ag
DD218283A1 (de) * 1983-05-31 1985-02-06 Kali Veb K Vorrichtung zur steuerung mehrerer schaelschleudern
DE3515915C2 (de) * 1985-05-03 1993-10-14 Braunschweigische Masch Bau Überwachungsverfahren und Vorrichtung zur Kontrolle des Sirupablaufes bei periodisch arbeitenden Zuckerzentrifugen
GB8517762D0 (en) * 1985-07-15 1985-08-21 British Nuclear Fuels Plc Centrifuges
DE3615013C1 (en) * 1986-05-02 1987-06-11 Krauss Maffei Ag Method for monitoring the drying phase in filtration centrifuges
DE3632176A1 (de) * 1986-09-22 1988-04-07 Fresenius Ag Steuerung eines systems zur trennung der bestandteile des einem spender "in vivo" entnommenen blutes
DE3726227A1 (de) * 1987-08-07 1989-02-16 Krauss Maffei Ag Vorrichtung zum ergebnisabhaengigen steuern einer filterzentrifuge
DE3822225C1 (ja) * 1988-07-01 1989-07-20 Laboratorium Prof. Dr. Rudolf Berthold, 7547 Wildbad, De

Also Published As

Publication number Publication date
DE59004414D1 (de) 1994-03-10
DE3940057C2 (ja) 1993-08-05
JPH03270750A (ja) 1991-12-02
ES2048391T3 (es) 1994-03-16
DE3940057A1 (de) 1991-06-06
US5093010A (en) 1992-03-03
EP0431426A1 (de) 1991-06-12

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